Plastics have become a staple construction material in the construction of all types of buildings, from single-family homes and offices complexes to industrial and chemical plants. Concern over flammability of the plastics used in the construction has lead to the widespread use of halogenated plastics, such as polyvinyl chloride in the construction industry due to their comparatively low flammability. Further development has resulted in incorporation of a halogen into other plastics as a means for reducing their flammability.
More recently, the concern over increased use of plastics in the construction of dwellings and other structures has shifted from concern over flammability to concern over the amount of smoke generated by the plastics during combustion, particularly halogenated plastics which generate a comparatively high amount of smoke. These concerns have lead to building code standards for maximum flame spread/smoke development of 25/50 as measured by ASTM E-84, for plastics used in construction.
A number of smoke suppressant additives for plastics have been suggested.
King, U.S. Pat. No. 3,900,441, discloses a smoke suppressant composition for plastics comprising a mixture of a zinc compound, such as zinc oxide, and a molybdenum compound having the molybdenum ion in the 6.sup.+ valence state, such as sodium molybdate.
Schwarcz et al, U.S. Pat. No. 3,945,974, discloses a smoke suppressant composition for plastics comprising a zinc compound capable of producing zinc oxide during combustion.
Kay, U.S. Pat. No. 3,957,723, discloses a smoke suppressant composition for plastics comprising a mixture of aluminum oxide trihydrate and zinc oxide.
Dickens, U.S. Pat. No. 3,965,068, discloses a smoke suppressant composition for plastics comprising a mixture of a nickel compound and a zinc compound.
Elcik, U.S. Pat. No. 3,983,290, discloses a smoke suppressant composition for plastics comprising a mixture of magnesium hydroxide, zinc borate and antimony trioxide.
Kay, U.S. Pat. No. 3,985,706, discloses a smoke suppressant composition for plastics comprising a mixture of aluminum oxide trihydrate and zinc borate.
White et al, U.S. Pat. No. 3,996,142, discloses a smoke suppressant composition for plastics comprising the reaction product of magnesium oxide and a zinc salt and optionally an antimony compound.
Kroenke, U.S. Pat. No. 4,055,537, discloses a smoke suppressant composition for plastics comprising a mixture of a melamine molybdate or substituted melamine molybdate and at least one compound selected from the group consisting of molybdenum carbonate, zinc oxide, zinc borate, zinc silicate, and others.
Barr, U.S. Pat. No. 4,079,033, discloses a smoke suppressant composition for plastics comprising iron oxalate, zinc oxalate, zinc octoate, or mixtures thereof.
Deets, U.S. Pat. No. 4,080,404, discloses a smoke suppressant composition for plastics comprising dawsonite, magnesium, carbonate, ferric oxalate, zinc borate, zinc acetate or a mixture of zinc oxide and magnesium oxide.
Lawson, U.S. Pat. No. 4,096,116, discloses a smoke suppressant composition for plastics comprising a mixture of aluminum hydroxide and at least one of a cobalt, zinc, iron or manganese salt of hydroxycarboxylic or dicarboxylic acids.
Nichols, U.S. Pat. No. 4,097,432, discloses a smoke suppressant composition for plastics comprising a mixture of a specific organic compound and an oxide, hydroxide or salt of Fe .sup.+++, Zn.sup.++, or mixtures thereof.
Mathis, U.S. Pat. No. 4,104,233, discloses a smoke suppressant composition for plastics comprising omegabromoalkyl esters of saturated aliphatic dicarboxylic acids and optionally an oxide, hydroxide, hydrate or salt of antimony, aluminum, calcium or magnesium.
Elcik, U.S. Pat. No. 4,129,535, discloses a smoke suppressant composition for plastics comprising a mixture of magnesium hydroxide, zinc borate, and antimony trioxide.
Joyce II et al , U.S. Pat. No. 4,260,542, discloses a smoke suppressant composition for plastics comprising the reaction product of one or more phosphorus compounds and certain metal oxides, metal salts, ammonia salts or silicon salts.
Davis et al, U.S. Pat. No. 4,272,427, discloses a smoke suppressant composition for plastics comprising a mixture of magnesium carbonate and zinc carbonate.
Huang et al, U.S. Pat. No. 4,360,624, discloses a smoke suppressant composition for plastics comprising a solid solution of zinc oxide and magnesium oxide and/or calcium oxide and/or an antimony compound.
Jacobs, U.S. Pat. No. 4,464,502, discloses a smoke suppressant composition for plastics comprising zinc oxide and optionally calcium carbonate or magnesium oxide.
Gupta, U.S. Pat. No. 4,593,060, discloses a smoke suppressant composition for plastics comprising tin or calcium oxalate and optionally zinc, magnesium or titanium oxide.
To my knowledge, none of the currently known smoke suppressants are capable of achieving the 25/50 ASTM E-84 class A standard without creating significant decomposition and/or coloration problems during processing or use.
Accordingly, a substantial need exists for an affordable smoke suppressant composition capable of reducing the smoke development of a plastic below the class A standard of 50, as measured by ASTM E-84, without significantly affecting the appearance or integrity of the plastic.